Prosecutors are investigating whether Belgian banks paid out interest and dividends on accounts frozen under UN sanctions in 2011 after the ouster of the Libyan leader Muammar Gaddafi.

Up to €5 billion ($5.7 billion) could have been disbursed to people controlling Libyan accounts, including militia groups in the country which stand accused of human rights abuses, according to a report by public broadcaster RTBF which cited an unidentified source.

RTBF said that when the UN agreed to freeze deposits held by Gaddafi’s administration abroad, Belgium had done so but had not halted payments of interest and dividends.